Question: Impetigo

C) Polymyxin B
Polymyxin B has efficacy against gram negative organisms only. While bacitracin and neomycin have some efficacy against gram positive and gram negative organisms, they are inferior to mupirocin for treatment of impetigo, and are not recommended. Additionally, neomycin has a high rate of causing contact dermatitis. Mupirocin and Retapamulin are both indicated for treatment of impetigo, and mupirocin has the advantage of treating MRSA. Retapamulin may be efficacious for some organisms resistant to mupirocin but is expensive. Mupriocin and Retapamulin are prescription, while the others are available over the counter, often in combination with each other. Confusion may arise because a brand name of mupirocin is Bactroban, which can be confused with Bacitracin.